The invention relates to a connecting assembly between a shaft journal and a constant velocity universal joint, more particularly in the driveline of a motor vehicle. The constant velocity universal joint comprises an outer joint part which can be connected to a driveshaft for example; an inner joint part which is engaged in a rotationally fixed way by the shaft journal for transmitting torque; as well as torque transmitting elements which are effective between the outer joint part and the inner joint part. The shaft journal can be the input part or output part of a gearbox, more particularly of an axle differential or of a manual gearbox, so that the shaft journal is axially and radially fixed. Accordingly, the constant velocity universal joint can be positioned at one end of a propeller shaft. The shaft journal can also be supported in an elastic intermediate bearing, with the constant velocity universal joint then being used as the central joint of a two-part propeller shaft.
From DE 10 2004 048 079 A1, there is known a connecting assembly between a constant velocity universal joint which is arranged at the end of the propeller shaft and an axially fixed shaft journal of a gearbox. By means of longitudinal splines, the shaft journal engages an inner joint part of a constant velocity joint in a rotationally fixed way. The propeller shaft comprises a threaded portion on to which there is threaded a threaded sleeve. The threaded sleeve engages a threaded recess of the inner joint part, with a securing ring arranged in the threaded recess axially fixing the inner joint part relative to the threaded sleeve.
From DE 10 2004 009 477 B4, there is known a further connecting assembly between a constant velocity universal joint and a shaft journal. There is provided a sleeve which is firmly connected to the inner joint part and engages an annular groove of the shaft journal, so that there is achieved an axially effective engaging connection. The sleeve is radially secured by a tensioning band in the region of the engaging connection.
Overall, connecting a constant velocity universal joint to a shaft journal is complicated because there is available only a limited amount of space and the final assembly stage is also complicated. At the same time, the connecting assembly between the constant velocity universal joint and the shaft journal is subject to optimum safety regulations to prevent disconnection and to ensure minimum adverse effects on the strength of the components.
The present invention provides a connecting assembly between a constant velocity universal joint and a shaft journal, wherein the connecting assembly has a compact design, permits secure axial fixing conditions and ensures a minimum effect on the shaft strength, with easy assembly and dismantling procedures being ensured as well.
The connecting assembly, more particularly for use in the driveline of a motor vehicle, comprises a shaft journal with an outer journal groove; a constant velocity universal joint with an inner joint part which is connected to the shaft journal in a rotationally fixed way for transmitting torque, wherein the inner joint part comprises a sleeve-like portion with an inner annular groove; a radially elastically widenable axial securing ring which is provided for axially fixing the inner joint part and which is positioned in the journal groove of the shaft journal; and securing means which are arranged on the sleeve-like portion and prevent the axial securing ring from being radially widened.
The advantage of the inventive connecting assembly is that there are achieved secure axial fixing conditions between the inner joint part and the shaft journal. More particularly, if there occur centrifugal forces or if axial forces are introduced into the connecting assembly, the securing means offer an effective protection against radial widening of the axial securing ring and thus a reliable connection. Furthermore, the inventive assembly only has a minimum effect on the strength of the shaft journal, because it is possible to use axial securing rings whose shape requires only a slight reduction in the cross-section of the shaft journal. The depth of the journal groove into which the axial securing ring snaps is preferably smaller than the depth of the inner annular groove of the sleeve-like portion. A further advantage refers to the simple design of the connecting assembly which comprises only few parts, which has an advantageous effect on production costs. The assembly requires a small installation space only and the components are easy to mount. More particularly, the constant velocity universal joint can be completely pre-assembled, so that, during the final assembly stage, only the connection between said joint and the shaft journal has to be effected.
For assembly purposes, the axial securing ring is inserted into the annular groove of the sleeve-like portion, and the inner joint part and thus the entire constant velocity universal joint is slid onto the shaft journal. The axial securing ring is preferably radially widened by an end cone of the shaft journal and snaps inwardly when it reaches the journal groove. In this way, the axial securing ring is radially inwardly pretensioned, i.e. it is positioned with pretension in the journal groove. If required, the connecting assembly can be easily released by elastically widening the axial securing ring, with the functioning ability of the individual components being fully retained.
The shaft journal can preferably be the input part or output part of a gearbox. If the shaft journal constitutes the input part, it can be used in an axle differential, for example, which serves to distribute the introduced torque from the propeller shaft to two sideshafts. In the form of an output part, the shaft journal can be used in a manual gearbox, for example, from where the torque is introduced into the propeller shaft. The gearbox is incorporated before the driveshaft is mounted, so that the shaft journal is axially and radially fixed in the gearbox housing.
According to a first embodiment, the axial securing ring is provided in the form of a snap ring, i.e. an open ring. According to a second embodiment, the axial securing ring is provided in the form of a continuously closed ring.
If a snap ring is used, it is particularly advantageous if said snap ring, and optionally also the journal groove, comprise a rectangular profile. The rectangular profile ensures that, if axial forces occur between the inner joint part and the shaft journal, there will not occur a sliding movement at the contact faces and thus no radial widening of the snap ring. However, any other cross-sectional shapes are conceivable, for example round, oval or trapezoidal cross-sections. For handling purposes, it is particularly advantageous if the at least two outwardly projecting portions form the ends of the open snap ring. The sleeve-like portion of the inner joint part, in a partial circumferential region of the inner annular groove, comprises a recess towards the outer circumferential face in which the ends of the snap ring are received. Said recess extends in the axial direction, preferably as far as the end face of the sleeve-like portion, so that there is formed a free space for mounting and dismantling purposes. For securing the connecting assembly, it is particularly advantageous if the ends of the snap ring project radially at least as far as the outer circumferential face, when the snap ring engages the journal groove.
If a closed ring is used, the cross-section of the same is preferably shaped in such a way that an axial relative movement of the ring relative to the shaft journal causes a radial-elastic widening of the ring. This can be achieved, for example, by a round, an oval or a trapezoidal cross-section of the securing ring. The advantage of said embodiment is that, by applying an axial force, the assembly can be easily dismantled provided the securing means for preventing the securing ring from widening have been removed.
According to an advantageous further design, which applies to the first and the second embodiment, the outwardly projecting portions are provided in the form of circumferentially distributed bulging portions of the axial securing ring. In principle, the number of bulging portions which are preferably uniformly distributed around the circumference, can be freely selected, with a number of at least three, preferably four, radial bulging portions being advantageous for the purpose of centring the axial securing ring relative to the inner joint part. In partial circumferential regions of the inner annular groove, the sleeve-like portion of the inner joint part preferably comprises a plurality of recesses towards the outer circumferential face and end face of the sleeve-like portion, into which the bulging portions of the axial securing ring are able to extend. In a cross-sectional view, the recesses are just large enough to accommodate the bulging portions extending into same without having any space to allow elastic deformation. To achieve simple securing conditions it is advantageous if the bulging portions are designed in such a way that their outer end faces at least radially extend as far as the outer circumferential face of the sleeve-like portion, when the axial securing ring is in an engaging condition in the journal groove. If an open ring with bulging portions is used, the opening slot is preferably located in the circumferential direction between two adjoining bulging portions.
According to a preferred design which also applies to both the above-mentioned embodiments, the securing means are provided in the form of a sleeve element to prevent the axial securing ring from widening in the radial direction. Said sleeve element is positioned on the sleeve-like portion of the inner joint part and covers the at least one recess. In the slid-on condition of the sleeve element, the outwardly projecting end portions of the open ring, respectively the bulging portions of the closed ring rest against the inner face of the sleeve element, thus preventing the axial securing ring from widening. Particularly good securing conditions are achieved if the sleeve element is reinforced in the region of overlap with the ends of the open securing ring and, respectively, with the bulging portions of the closed securing ring, for example by an inner reinforcing ring. The slid-on sleeve element, which can also be denoted securing sleeve or collar, ensures in an advantageous way that radial widening of the axial securing ring is prevented at least to the extent that it can no longer be pressed out of the journal groove. The sleeve element preferably comprises an inner annular bead which, for axial securing purposes, engages an outer annular groove of the sleeve-like portion. The sleeve element is fixed by a binding element which, more particularly, is designed in such a way that it can only be closed if the sleeve element is accurately positioned on the sleeve-like portion. This measure prevents unintentional incorrect mounting.
According to a preferred design which applies to all the above-mentioned embodiments there are provided shaft splines in order to achieve a rotationally fixed connection between the inner joint part and the shaft journal, with the annular groove, into which the axial securing ring is inserted, being arranged so as to axially adjoin the shaft teeth. The annular groove is easier to produce because it is not positioned inside the shaft teeth. In a preferred embodiment, the inner joint part comprises a ball track portion in which there are formed inner ball tracks, with the shaft splines axially extending beyond the ball track portion as far as the inside of the sleeve-like portion of the inner joint part. This measure of providing extended shaft splines allows the transmission of particularly high torque values. Furthermore, it is proposed that, in the region of the sleeve-like portion, the inner joint part comprises an outer annular groove in which there is fixed an inner shoulder of a sealing collar by means of a clamping ring. The joint designed in this way can be completely pre-assembled prior to being connected to the shaft journal. By providing the sealing collar in the form of a diaphragm boot, it is possible to achieve a particularly compact design.